As technology for supporting speeding up of information communications and long-distance transmission paths, error correction processing is well known. The error correction processing applies error correction codes in order to correct bit errors with respect to a signal that is transmitted through a transmission path and received at the reception terminal. The necessity of error correction processing is heightened by the fact that the ability of the element(s) constituting the reception apparatus that receives a signal affects the received signal quality. Recently, with speeding up and enlargement of the capacity of information transmission by means of optical communications, the requirements for the received signal quality become severe, and the ability of error correction processing is required to be improved.
Then, the circuit module such as LSI (Large Scale Integration) that carries out such error correction processing is required to perform further complex arithmetic operations accompanying the improvement of the correction processing ability. Because of this, the circuit module of the error correction processing has a tendency such that the larger the gate scale, the larger the power consumption.
Here, the transmission path applied to an information communications system has factors that vary the transmission characteristics in its operation, and such variation factors affect the received signal quality. The paths transmitting wavelength multiplexed optical signals therethrough are not exceptions.
For example, the wavelength dispersion characteristic varies depending on the temperature state, which affects the received signal quality at the reception terminal. Further, in the wavelength multiplexed signal, an optical signal at one wavelength is affected by the non-linear effects such as mutual cross phase modulation or the like with an optical signal at another wavelength. Further, the variations in temperature in the room in which an optical reception apparatus is installed also affect the received signal quality.    (Patent Document 1) Japanese Patent Application Publication No. 2006-332920    (Paten document 2) Japanese Patent Application Publication No. HEI 6-302085